## Abstract

The pulmonary O _{2} diffusing capacity (DO _{2}) can be estimated in man from the kinetics of PO _{2} equilibration between lung gas and mixed venous blood during a rebreathing maneuver, when the following variables are known or can be simultaneously determined: mean rebreathing bag volume (VR), mean lung volume (VA), effective ventilation ([rate of change of V]eff), pulmonary capillary blood flow [rate of change of Q], and slope of the blood O _{2} dissociation curve (βO _{2}). Two rebreathing maneuvers, both performed after breathing 11.5% O _{2} in N _{2} at steady state, are required. In the first maneuver, an appropriate volume of 8% CO _{2} in N _{2} is rebreathed for determination of mixed venous blood PO _{2} (P(average V)O _{2}). V)O2. The second maneuver, in which a mixture containing 8% O _{2}, 7% CO _{2}, 20% N _{2}O and 10% He in N _{2} is rebreathed, allows the determination of the remaining variables: the rate constant of PO _{2} equilibration (KO _{2}) from the exponential approach of lung PO _{2} to P(average V)O _{2}; Va and [rate of change of V]eff, from He dilution and mixing rate; [rate of change of Q], from the transfer rate of N _{2}O. The mean DO _{2} value found in 19 experiments on 4 healthy young males at rest was 31 ml/min ^{-1}/Torr ^{-1}. The validity and the applicability of the method are critically discussed.

Original language | English |
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Pages (from-to) | 526-532 |

Number of pages | 7 |

Journal | Journal of Applied Physiology |

Volume | 37 |

Issue number | 4 |

Publication status | Published - 1974 |

## ASJC Scopus subject areas

- Physiology
- Endocrinology
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation